The present invention relates to devices for aiding in the navigation of a vehicle, and more particularly, to an optical system for an automobile which aids the driver in judging the proximity of the forward end of the automobile to an object directly in front of the automobile when parking close to a wall or when pulling up close behind another automobile stopped at an intersection.
For many years automobiles have had long horizontally extending hoods. A person driving such an automobile could easily judge the depth of the forward end of the automobile, even if he or she couldn't see the front bumper, by focusing on the front end of the hood. The continual effort to increase automobile milage has resulted in automobiles now in widespread use that have steeply sloped or wedge-shaped forward ends to minimize aerodynamic resistance. The forward end of such an automobile, typically the leading edge of its front bumper, is not visible to the driver from his or her normal seated position in the driver's seat. Since this type of automobile has a front hood which "falls off" or descends rather dramatically from the windshield it is extremely difficult for the driver to judge the distance between the forward end of the automobile and an object immediately in front of the automobile. This makes it difficult to park close to a wall or barricade in front of the automobile without bumping it. It also makes it difficult to pull up close to another automobile stopped at an intersection.
A number of optical systems have been developed in the past for aiding a driver in reading the instrumentation of an automobile without having to look down, for judging the distance to a preceding automobile when traveling down the highway, or for aiding in backing up a motor vehicle. However, none of these systems is adapted to aid a driver in positioning the forward end of his or her car close to another object.
U.S. Pat. No. 1,871,877 of Buckman, U.S. Pat. No. 3,848,974 of Hosking et al., and U.S. Pat. No. 3,887,273 of Griffiths disclose different approaches for "heads up" speedometer display. An image of the speedometer is projected onto the interior surface of the windshield so that the driver need not look away from the road to check the speed of the automobile.
U.S. Pat. No. 1,879,592 of Thomas, U.S. Pat. No. 3,521,234 of Davin, U.S. Pat. No. 3,670,423 of Leber, U.S. Pat. No. 3,772,795 of Calvet, U.S. Pat. No. 3,859,732 of Davin, and U.S. Pat. No. 4,417,404 of Doberschutz disclose various scales which are affixed on the windshield, rear window or rear view mirror and used by a driver to determine the distance between his or her car and objects ahead or behind his or her car.
U.S. Pat. No. 4,257,706 of Smith discloses a pair of rods or sights at spaced locations on the side of a truck which are aligned with a ground line of a wall by the driver looking in a rear view mirror to position the rear end of the truck closely adjacent to the wall.
U.S. Pat. No. 3,715,721 of Irving et al. discloses another system for allowing a driver to judge a safe following distance from a preceding vehicle. An illuminated drum driven by the vehicle gear box projects images of index lines onto a reflective surface beneath the windshield. To the driver these images are seen at infinity and they move together in a manner proportional to an increase in the vehicle's speed to warn the driver that he or she must increase the distance of separation between his or her car and any vehicle that is being followed.
Finally, U.S. Pat. No. 3,762,802 of Allen discloses a rotatable mirror mounted to the front end of an automobile for enabling the driver to view otherwise blind areas, particularly in parking or in driving out of blind driveways.